Large quantities of hydrate-forming binders, such as cement, lime and gypsum materials, for example, are used in the construction industry.
As gypsum materials, calcined gypsum and plaster are used, either alone or in combination with lime, sand and lightweight aggregates. However, the setting times for these gypsum materials once they have been mixed with water are relatively short, so that, unless additional measures are implemented, processing must be carried out very quickly. However, it is known to delay the onset of solidification of gypsum materials by mixing these materials with setting retarders, thereby improving their processability. Known setting retarders include, for example, fruit acids, such as tartaric acid and citric acid, but also protein hydrolyzates, such as the commercially available Plast Retard L (obtainable from Sicit 2000 S.p.A.).
In this connection, EP 2 108 628 A1 (Tricosal GmbH) describes, for example, a setting retarder in the form of an adduct based on an amino acid compound and a carboxylic acid or a carboxylic acid derivative. This adduct is produced by reacting an amino acid compound with a carboxylic acid or a carboxylic acid derivative in an aqueous solution.
Although known setting retarders are highly effective, the need still exists for an improved setting retarder which will further retard, in particular, the onset of solidification after being mixed with water.